Synthetic approaches tb mycorrhizin A and gilmicolin. II. Early introduction of a C3 side chain into a benzofuranol precursor

1983 ◽  
Vol 36 (6) ◽  
pp. 1263 ◽  
Author(s):  
RFC Brown ◽  
GL Edwards ◽  
CM Jones ◽  
ID Rae ◽  
PYT Teo
Keyword(s):  
Side Chain ◽  
Early Introduction ◽  
Allyl Compound ◽  
Original Scheme ◽  
Synthetic Approaches ◽  
System 1

An attempt to modify the previously reported synthesis of the tricyclic system (1) of mycorrhizin A (2) and gilmicolin (3) by very early introduction of a C3 side chain is described. However, both 6-(2-acetoxypropyl)-7a-methoxy-2,2-dimethylbenzofuran-4,7(2H,7aH)-dione (21) and the corresponding 6-allyl compound (24) fail to add cyclopentadiene as required for protection of the enedione system in the original scheme.

scholarly journals New Zampanolide Mimics: Design, Synthesis, and Antiproliferative Evaluation

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 362 ◽  
Author(s):  
Guanglin Chen ◽  
Ziran Jiang ◽  
Qiang Zhang ◽  
Guangdi Wang ◽  
Qiao-Hong Chen
Keyword(s):  
Multidrug Resistant ◽  
Side Chain ◽  
Drug Candidate ◽  
Design Synthesis ◽  
Asymmetric Dihydroxylation ◽  
Synthetic Approaches ◽  
Further Development ◽  
Covalent Nature ◽  
Microtubule Stabilizing Agent ◽  
Unique Chemical

Zampanolide is a promising microtubule-stabilizing agent (MSA) with a unique chemical structure. It is superior to the current clinically used MSAs due to the covalent nature of its binding to β-tubulin and high cytotoxic potency toward multidrug-resistant cancer cells. However, its further development as a viable drug candidate is hindered by its limited availability. More importantly, conversion of its chemically fragile side chain into a stabilized bioisostere is envisioned to enable zampanolide to possess more drug-like properties. As part of our ongoing project aiming to develop its mimics with a stable side chain using straightforward synthetic approaches, 2-fluorobenzyl alcohol was designed as a bioisosteric surrogate for the side chain based on its binding conformation as confirmed by the X-ray structure of tubulin complexed with zampanolide. Two new zampanolide mimics with the newly designed side chain have been successfully synthesized through a 25-step chemical transformation for each. Yamaguchi esterification and intramolecular Horner–Wadsworth–Emmons condensation were used as key reactions to construct the lactone core. The chiral centers at C17 and C18 were introduced by the Sharpless asymmetric dihydroxylation. Our WST-1 cell proliferation assay data in both docetaxel-resistant and docetaxel-naive prostate cancer cell lines revealed that compound 6 is the optimal mimic and the newly designed side chain can serve as a bioisostere for the chemically fragile N-acetyl hemiaminal side chain in zampanolide.

scholarly journals A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

2021 ◽  
Vol 17 ◽  
pp. 2932-2938
Author(s):  
Haopei Wang ◽  
Zachary T Ball
Keyword(s):  
Structure And Function ◽  
Side Chain ◽  
Cleavage Process ◽  
And Function ◽  
Synthetic Approaches ◽  
Formyl Peptides ◽  
Spatiotemporal Control

Photo-responsive modifications and photo-uncaging concepts are useful for spatiotemporal control of peptides structure and function. While side chain photo-responsive modifications are relatively common, access to photo-responsive modifications of backbone N–H bonds is quite limited. This letter describes a new photocleavage pathway, affording N-formyl amides from vinylogous nitroaryl precursors under physiologically relevant conditions via a formal oxidative C=C cleavage. The N-formyl amide products have unique properties and reactivity, but are difficult or impossible to access by traditional synthetic approaches.

scholarly journals A Perspective of Diverse Synthetic Approaches and Biological Applications of Vitamin K

2021 ◽  
Author(s):  
Satyanarayana Battula
Keyword(s):  
Vitamin K ◽  
Shikimic Acid ◽  
Bone Mineralization ◽  
Growth Control ◽  
Vascular Diseases ◽  
Functional Health ◽  
Side Chain ◽  
Organometallic Reagents ◽  
Acid Pathway ◽  
Synthetic Approaches

Vitamin-K is a demanding multi-functional health product in the market and belongs to a class of isoprenoid molecules that comprises methylnaphthoquinone (MK) unit attached to an isoprene side chain. They are fat soluble and differ in the extent of side chain & obtained in the nature as vitamin K1 (phylloquinone), menaquinone/vitamin K2, and other lipoquinones. Owing to their owned polyprenyl side chain, they are hydrophobic/lipophilic in nature. Generally, the synthesis of vitamin K and its variants suffers with isomerization (for example 11 isomers were identified for cis/trans MK-7). Naturally, in bio-systems vitamin K produces through shikimic acid pathway and terpene biosynthetic pathway for the synthesis of menaquinone part & prenyl side chain parts respectively. Menadione or its auxiliaries are commonly being used as substrates to the synthesis of vitamin K variants through the involvement of condensation reactions, Friedel-Craft alkylation’s, Claisen rearrangement, Diels-Alder reactions and others. Importantly, organometallic reagents, such as Grignard, Gilman, organotelluride and other reagents could be the promising and consistent choice of substrate to the synthesis of various vitamin K’s. Vitamin K is well known for blood coagulation. As an antihaemorrhagic vitamin, it’s also being the current interest for the treatment of bone and vascular diseases. In addition, vitamin k is indispensable for the activation of vitamin K dependent (VKD) proteins and that are present almost in all tissues and responsible for hemostasis, bone mineralization, arterial calcification, apoptosis, phagocytosis, growth control, chemotaxis, and signal transduction. This chapter summarizes various synthetic approaches of vitamin K & derivatives and their biological functions.

Synthetic approaches to unsaturated five-membered heterocycles containing both ring and side-chain phosphorus atoms

1985 ◽  
Vol 22 (2) ◽  
pp. 513-522 ◽  
Author(s):  
Md. Amin ◽  
David G. Holah ◽  
Alan N. Hughes ◽  
Thitima Rukachaisirikul
Keyword(s):  
Side Chain ◽  
Synthetic Approaches

Reaction of peri-Aminonaphthoquinones and Dihydroperimidinones with piperidine

1977 ◽  
Vol 30 (9) ◽  
pp. 2081 ◽  
Author(s):  
DW Cameron ◽  
EL Samuel
Keyword(s):  
Side Chain ◽  
Methyl Group ◽  
System 1

Reaction of methyl-substituted 5-amino-1,4-naphthoquinones with piperidine gave preferentially 3-piperidino derivatives. The corresponding orientation also resulted from amination of the dihydroperimidinone system (1), a slower process. When position 3 of the naphthoquinone was substituted by a methyl group, preferential side-chain amination of that group was observed.

Studies of Vegetative Plant Tissue Compatibility/Incompatibility: The Role of Acid Phosphatase in Lethal Cell Senescence in an Incompatible Heterograft

1980 ◽  
Vol 38 ◽  
pp. 530-531
Author(s):  
Randy Moore
Keyword(s):  
Acid Phosphatase ◽  
Thick Layer ◽  
Cell Necrosis ◽  
Enzyme Localization ◽  
Vegetative Plant ◽  
Cell Autolysis ◽  
Graft Interface ◽  
System 1 ◽  
Thin Fibril

Previous work has indicated that the graft incompatihility between Sedrmi telephoides and Solanum pennellil involves cell necrosis that results In a thick layer of collapsed cells at the graft Interface. This necrotic layer insulates the stock from the scion, which results in abscission of the Sedum scion after 4-6 weeks due to desiccation and starvation. Thus, cell autolysis (which is restricted to Sedum) characterizes the Incompatibility response in this system (1). In order to elucidate the events that lead to cell autolysis, and thus better understand the cellular site and mode of action of cellular incompatibility, the appearance and fate of the hydrolytlc enzyme acid phosphatase (AP) was followed in both the compatible Sedum autograft and the incompatible Sedum/Solanum heterograft. Acid phosphatase was localized by a modified Gomori-type reaction; positive (i.e., including NaF inhibitor) and negative (lacking substrate) controls showed no enzymatic precipitate. Following an initial association with the endoplasmic reticulum (ER) and dictyosomes at 6-10 hours after grafting, AP activity in the compatible Sedum autograft is associated primarily with the plasmalemma (Fig. 1). By 18-24 hours after grafting, the AP activity is restricted to the tono-plast and vacuole (Fig. 2). This strict compartmentation and absence of enzyme from the cytosol is maintained throughout the development of the compatible graft. While AP activity in the incompatible Sedum/Solanum heterograft is Initially similar to the compatible Sedum autograft (i.e., initially found on the ER and dictyosomes), there is a marked difference in enzyme localization in the two graft partners as the incompatibility response develops. As in the compatible autograft, Solanum cells at the graft interface show an Increase in AP activity that Is restricted to the vacuole and tonoplast, with little or no enzyme activity in the cytosol (Fig. 3). In comparable Sedum cells, however, there is a dramatic Increase In AP activity in the cytosol (Fig. h); this cytosollc AP activity is associated with thin fibril-like structures (Fig. 5) measuring approximately 60 A in diameter. This high cytoplasmic AP activity In Sedum cells results in cell autolysis, death, and eventual cell collapse to form the characteristic necrotic layer separating the two graft partners.

Pyridyl disulfide-based thiol–disulfide exchange reaction: shaping the design of redox-responsive polymeric materials

2020 ◽  
Vol 11 (48) ◽  
pp. 7603-7624
Author(s):  
Ismail Altinbasak ◽  
Mehmet Arslan ◽  
Rana Sanyal ◽  
Amitav Sanyal
Keyword(s):  
Exchange Reaction ◽  
Functional Materials ◽  
Polymeric Materials ◽  
Disulfide Exchange ◽  
Redox Responsive ◽  
Synthetic Approaches

This review provides an overview of synthetic approaches utilized to incorporate the thiol-reactive pyridyl-disulfide motif into various polymeric materials, and briefly highlights its utilization to obtain functional materials.

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